Telephone Signalling Transceiver / Least Cost Router
CMX860
Note that allowance should be made for the transmit signal filtering in the CMX860 which attenuates the
output signal for frequencies above 2kHz by 0.25dB at 2.5kHz, by 1dB at 3kHz and by 2.2dB at 3.4kHz.
Receive Tone Pair Programming
th
The programmable tone pair detector is implemented as shown in Figure 9a. The filters are 4 order IIR
sections. The frequency detectors measure the time taken for a programmable number of complete input
signal cycles and compare this time against programmable upper and lower limits.
NB. If this register is not programmed, the detector will be configured to operate in its default mode,
which
is for the detection of 2130 Hz ± 20 Hz and 2750 Hz ± 30 Hz.
Figure 9a Programmable Tone Detectors
Figure 9b Filter Implementation
ã 2002 Consumer Microcircuits Limited
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D/860/5
CMLMICRO [ CML MICROCIRCUITS ]
